Due to a global trend of enforcing regulations of exhaust gasses of a vehicle, interest in environmentally-friendly vehicles is high. Vehicle manufacturing companies mass produce environmentally-friendly hybrid vehicles reflecting this interest in environmentally-friendly vehicles.
A hybrid vehicle may be distinguished from a fuel cell vehicle and an electric vehicle in a number of ways, but a hybrid vehicle in the present specification refers to a vehicle adopting an engine and a motor as power sources. That is, the hybrid vehicle has an electric travelling mode that is a motor driving mode for reducing consumption of fuel relative to a hybrid travelling mode that is an engine driving mode. Further, the vehicle may switch between the hybrid travelling mode and an electric travelling mode.
When the hybrid vehicle changes into the electric driving mode, the motor drives the vehicle, so that a release of a connection between the engine, which does not provide driving power, and a driving unit is required. That is, a release control of an engine clutch connecting the engine to the driving unit is performed.
However, vibrations are generated from an engine torque at the time at which the engine torque is converted to 0 in preparation for releasing the engine clutch. Accordingly, there is a problem in that a vibration of the vehicle is generated and an unpleasant driving environment is provided to a vehicle passenger during such a process.
However, when a release of the engine clutch is delayed, fuel is injected in the engine and a fuel driving state is maintained for the delayed time, so there is a problem in that fuel efficiency is reduced due to unnecessary fuel injection.
In order to solve the aforementioned problem, Japanese Patent Application Laid-Open No. 2007-0160991 (hereinafter, “Document 1”) that is the prior document provides a technology of detecting a change in demanded driving power by a driver and removing a sense of a travelling mode problem of a user while transiting between travelling modes when a hybrid travelling mode is switched to an electric driving mode.
However, Document 1 cannot provide a technology for revising an engine clutch release delay time by reflecting real-time engine torque information when the engine clutch is released.
In a case where the travelling mode of the hybrid vehicle is transited to the electric travelling mode, when the engine clutch release delay time is set, fuel is unnecessarily injected into the engine, so that there is a problem of a reduction of fuel efficiency.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.